That sounds funny...anyway, I currently have the 350cid/290hp GMPP crate engine and the 2 year warrenty is going to end July 31. The rockers are the stamped/stock rockers and I want to change it to rollers. But in order to do that, I have add a conversion kit to handle to roller rockers.....I wanted something simplier....found these "roller tipped" rockers from Summit Racing.

or these....


Has anyone done this? And if so, is it a swap-out from the stamped rockers.....any tricks or problems? Increase in HP? Any difference between Summit Racing and Comps?

Thanks!

 

Roller TIP, not "rollers" (full roller rockers)

In my experience at your power level and RPM range there are zero benefits. If you're looking for more power, seek elsewhere.

I'm sure this will start a huge debate about roller tips having "less friction", roller rockers adding HP, etc. and follow the predictable pattern we've all come to know and love

 

Your better off going with a full roller rocker configuration. Roller Tip Rockers will offer you little benefit. Depending on your setup, you could upgrade to 1.6, etc.

 

Curious - for what reasons would you run full rollers on a 290HP (flywheel) engine that likely never turns more than 5500 RPM?

 

Just want to improve the engine w/o tearing it down and putting mega bucks in it. The old adage....."every little bit helps"

 

listen to billa...good advice...put your money somewhere else.....the only posible edge you would gain is if the geometry varies on your stock rockers..friction is not an issue here....

 

I agree that stamped rockers are fine with his config. I would think the only added benefit at this point with full roller rockers would be less friction meaning a lower oil temp. It is mechanically a better sound setup. It makes more sense to me that if your going to spend the money to purchase roller tipped rockers you might as well spend a little more and go with full roller rockers. In any case, as mentioned, if your looking to increase HP there are better ways of doing that...

 

At this stage, roller rockers will improve nothing. You may as well flush your money down the toilet. It would be less work.

 

A set of headers to compliment your true dual exhaust would be a much better investment for power.

 

The new 427ci 600+HP LS7 Corvette uses roller rockers, the roller is in the fulcrum, there is no roller on the tip, you might read something into this

http://www.hotrod.com/techarticles/e.../photo_07.html

 

I think the biggest advantage an aftermarket rocker arm offers is that the ratio is typically as advertised. if they say it's 1.5:1, it is. Factory rocker arms have a wider tolerance in regards to ratio. This factor doesn't come in to play much with your engine in its current configuration. As you add more power, it could eventually be something you want to look at.

 

Thanks Guys for the input....gonna scrap the rocker idea and look at headers.

 

350/290 w/ rather low compression dish pistons & 76cc heads ... combo mimics L48 w/ L82 cam.

Leave the rockers alone; others explained why.

It already has a decent cam but low compression. Vortec heads will wake it up. Maybe 350HO would've been better choice. Save up for vortec head & intake swap. Otherwise, leave it alone & drive & enjoy.

 

Now days just about every engine manufacturer uses some version of the roller rocker - we have advanced that far. A quality roller rocker, either full, or tip only does offer an advantage over the stamped steel version on the OP's GMPP 290. The ratio will be true and consistent for all 16, they will not flex or flop off center, add a set of hardened push tubes and you get a good boost in power above 5,000 RPM. Why not do it? My '96 LT4 has then from the factory.

 

What do you consider to be a "good boost in power"? 1 hp? 2 hp?

 

1 or 2 hp sounds about right at high RPM on that motor. The new stamped rockers are much more consistant than they were 40 years ago. Not worth the effort, time and money. Headers will probably give you 20 to 40 HP over stock manifolds. That is worth it!

 

I'll respectfully disagree. Can you advise in your experience how many GEN I's have had rockers "flop off center"? What kind of "good boost in power" are you purporting?

Yes, a quality aftermarket stamped-steel rocker is going to be dead-on in terms of ratio and it is going to be stiffer. A quality aftermarket roller-tip is going to be even stiffer, and a full roller even stiffer than that. When we start turning serious RPM (6,000+ continuous), start pushing against serious valvespring pressure (140#+ with roller cams) and riding steep lobe ramps - valvetrain stiffness, friction and weight starts being a real issue as we try to keep the valvetrain stable at the limits of the engine's abilities.

But let's get real - the 350/290's valve springs (94666580) are 90# at installed height, and the HP peak is at 5250 RPM! The LT4 is making 330HP at 5800 RPM with a 6300 RPM redline, so there's just no comparison. It's worth noting that the LT1 had stamped-steel rockers, and the ONLY reason they were changed in the LT4 was that there were galling issues....at 6300 RPM! And note that this is with a fairly steep hydraulic roller cam.

Hardened pushrods are used with guideplates; they aren't any more stiff. If stiffer pushrods are needed, then the diameter is increased.

There's good advice for finding power on the thread - headers would be a definite first, followed IMHO by a solid tune. A top with cam would be next, but I'd stay on the low end of the price spectrum given the cast crank; the Vortec suggestion would be mine as well. Better, in the end I think, to simply enjoy the engine the way it is. It's a pretty sweet 350

 

Just do the Full aluminum heads, roller rockers and headers swap now! you know you want too......

 

They all do. If you think other wise just watch them. This type of rocker arm / valve stem contact is probably one of the worst devised.
A good boost in power on a 290 hp engine is 8 to 12 in my opinion. It's worth a tenth in the 1/4 mile - and it's your choice to do it or not do it. Headers are a given, but when you get done with the quick and easy stuff like exhaust and timing curve and carb jetting and are looking for something to compliment it all, why not do the rockers and push rods? On a little Chevy it's less than $200 and a couple hours work. And really, why even debate this, it has been proven many times on a dyno that the rockers and push rods will increase power even at 5,000 RPM.
Hardened push rods are stiffer than the stock ones. Increased diameter would be one way to increase the strength, but so is a stronger material.

It looks like your point is that there little to no gain in power. I say there is a gain and it's worth the price.
Let's leave it at that.

 

Honestly, there's so much bad information there I don't know where to start. I agree that it doesn't make a lot of sense to debate as clearly we have dramatically different experience and expertise

"Worst devised." Hmm. What were those GM engineers thinking making 90 million or so engines over 50 years with this design and fostering that junk on us?

But I think a simple request would be posting a a single link (of the "many times") to a dyno test where this is 8-12 HP is "proven" for a GEN I, hydraulic flat-tappet cam engine making < 1 HP/CID?